title: Dose-dependent thresholds of 10-ns electric pulse induced plasma membrane disruption and cytotoxicity in multiple cell lines.
abstract: In this study, we determined the LD(50) (50% lethal dose) for cell death, and the ED(50) (50% of cell population staining positive) for propidium (Pr) iodide uptake, and phosphatidylserine (PS) externalization for several commonly studied cell lines (HeLa, Jurkat, U937, CHO-K1, and GH3) exposed to 10-ns electric pulses (EP). We found that the LD(50) varied substantially across the cell lines studied, increasing from 51 J/g for Jurkat to 1861 J/g for HeLa. PS externalized at doses equal or lower than that required for death in all cell lines ranging from 51 J/g in Jurkat, to 199 J/g in CHO-K1. Pr uptake occurred at doses lower than required for death in three of the cell lines: 656 J/g for CHO-K1, 634 J/g for HeLa, and 142 J/g for GH3. Both Jurkat and U937 had a LD(50) lower than the ED(50) for Pr uptake at 780 J/g and 1274 J/g, respectively. The mechanism responsible for these differences was explored by evaluating cell size, calcium concentration in the exposure medium, and effect of trypsin treatment prior to exposure. None of the studied parameters correlated with the observed results suggesting that cellular susceptibility to injury and death by 10-ns EP was largely determined by cell physiology. In contrast to previous studies, our findings suggest that permeabilization of internal membranes may not necessarily be responsible for cell death by 10-ns EP. Additionally, a mixture of Jurkat and HeLa cells was exposed to 10-ns EP at a dose of 280 J/g. Death was observed only in Jurkat cells suggesting that 10-ns EP may selectively kill cells within a heterogeneous tissue.
authors.affiliation: 711th Human Performance Wing, Radio Frequency Radiation Branch, Air Force Research Laboratory, Brooks City-Base, San Antonio, Texas, USA. Bennett.Ibey@brooks.af.mil
authors.forename: Bennett L
authors.initials: BL
authors.lastname: Ibey
authors.forename: Caleb C
authors.initials: CC
authors.lastname: Roth
authors.forename: Andrei G
authors.initials: AG
authors.lastname: Pakhomov
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Bernhard
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Wilmink
authors.forename: Olga N
authors.initials: ON
authors.lastname: Pakhomova
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D016466:CHO Cells; D002118:Calcium / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D004558:Electric Stimulation; D004560:Electricity / Q000009:adverse effects*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D008027:Light; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D010718:Phosphatidylserines / Q000378:metabolism; D051381:Rats; D012542:Scattering, Radiation; D013997:Time Factors; D014357:Trypsin / Q000494:pharmacology
chemical_list: D017304:Annexin A5; D010718:Phosphatidylserines; D014357:Trypsin; D016650:Fluorescein-5-isothiocyanate; D002118:Calcium